Hamideh Javadi - Research Institute of Forests and Rangelands, Tehran, Iran

Chromosome numbers in 19 populations of Tanacetum polycephalum and Tanacetum parthenium from natural resources gene bank, that collected from different regions of Iran, were determined for the first time. The samples prepared by using root tips. After pretreatment, fixation, hydrolysis and staining, the microscopic samples prepared by squash method, metaphases were captured using an optical microscope. The best metaphases plates were selected and used for karyotype analyses. In all of populations the basic chromosome number was x=9 and the populations showed two ploidy levels (diploid & tetraploid). The type of the most chromosomes in all of the populations was metacentric (m) and sub-metacentric (sm) and located in 2A and 2B except for T. parthenium (Yazd, Taft) with 5m+3sm+1st karyotype formula and 2C Stebbins classes. In addition, T. polycephalum (Esfahan, Golpayegan) with the highest value of AR and A1 had karyotype heterogeneity, also T. polycephalum (Esfahan, Golpayegan) and T. polycephalum (West-Azerbaijan, Uromeyeh) had the highest value of chromosome length (TL). Detailed karyotype allows us to group the different populations based on Stebbins classes and asymmetry indices.

Chromosome numbers, Ploidy levels, Karyotype, Tanacetum polycephalum, Tanacetum parthenium, Microscopic samples, Squash method